How to Use This Manual
To collect and monitor Oracle Database metrics, the Oracle Database plug-in must be deployed to an agent. The Oracle Database plug-in depends on the EM Platform plug-in.
For information on plug-ins, see Plug-ins Included In This Release in Enterprise Manager Cloud Control Release Notes.
This preface describes:
Structure of the Metric Reference Manual
The metrics in each chapter are in alphabetical order according to category.
Metric Information
Where available, each metric includes the following information:
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Description
Explanation following the metric name. This text defines the metric and, where available, provides additional information pertinent to the metric.
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Metric Summary Table
Where available, this table lists the target version, default collection frequency, default warning threshold, default critical threshold, and alert text for the metric.
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Data Source
How the metric is calculated. In some metrics, data source information is not available.
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User Action
Suggestions of how to solve the problem causing the alert.
Examples of Metric Summary Tables
This section provides examples of Metric Summary tables that you will see in the Oracle Database Metric Reference Manual.
When default thresholds are not defined for a metric, only the target version and default collection frequency are available.
| Target Version | Collection Frequency |
|---|---|
|
All versions |
Every 15 minutes |
The following table shows a metric where the server evaluation frequency is the same as the collection frequency.
| Target Version | Evaluation and Collection Frequency |
|---|---|
|
All versions |
Every 10 minutes |
Definitions of Columns in Metric Summary Tables
As previously mentioned, the Metric Summary table is part of the overall metric information. The following table provides descriptions of columns in the Metric Summary table.
| Column Header | Column Definition |
|---|---|
|
Target Version |
Version of the target, for example, 18c. Note that if "All versions" is mentioned, then the metric is available for target version 11gR2 and later. |
|
Evaluation and Collection Frequency |
The rate at which the metric is collected and evaluated to determine whether it has crossed its threshold. The evaluation frequency is the same as the collection frequency. |
|
Collection Frequency |
The rate at which the Management Agent collects data. The default collection frequency for a metric comes from the Enterprise Manager default collection file for that target type. |
|
Default Warning Threshold |
Value that indicates whether a warning alert should be initiated. If the evaluation of the warning threshold value returns a result of TRUE for the specified number of consecutive occurrences defined for the metric, an alert triggers at the warning severity level. |
|
Default Critical Threshold |
Value that indicates whether a critical alert should be initiated. If the evaluation of the critical threshold value returns a result of TRUE for the specified number of consecutive occurrences defined for the metric, an alert triggers at the critical severity level. |
|
Alert Text |
Message indicating why the alert was generated. Words that display between percent signs (%) denote variables. |
About Metrics, Thresholds, and Alerts
A metric is a unit of measurement used to determine the health of a target. It is through the use of metrics and associated thresholds that Enterprise Manager sends out alerts notifying you of problems with the target.
Thresholds are boundary values against which monitored metric values are compared.
When a threshold is reached, Enterprise Manager generates an alert. An alert is an indicator signifying that a particular condition has been encountered and is triggered when one of the following conditions is true:
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A threshold is reached.
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An alert has been cleared.
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The availability of a monitored service changes. For example, the availability of an application server changes from up to down.
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A specific condition occurs. For example, an alert is triggered whenever an error message is written to a database alert log file.
Alerts are detected through a polling-based mechanism by checking for the monitored condition from a separate process at regular, predefined intervals.
Accessing Metrics
To access metrics from the Cloud Control Console, use the All Metrics page:
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From the Cloud Control Console, choose the target.
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From the target's home page, select the target type name, then Monitoring, and then All Metrics.
Editing Metrics
Out of the box, Enterprise Manager comes with default thresholds for critical metrics. Enterprise Manager generates alerts when warning and critical thresholds are reached, letting you know of impending problems so that you can address them in a timely manner.
To better suit the monitoring needs of your organization, you can edit the thresholds provided by Enterprise Manager and define new thresholds.
When defining thresholds:
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Choose acceptable values to avoid unnecessary alerts, while still being notified of issues in a timely manner.
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Adjust your metric thresholds based on metric trends. One of the more important actions you can perform with your monitoring system is to track metric trends for some period of time so you can make informed decisions about what metrics are important as well as what levels your thresholds should be set at.
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Set the number of occurrences appropriately. If some events occur only once or twice, for example, you might not need to be notified of them. You can set the number of occurrences of a metric that must be reached before you are notified.
To modify metric thresholds:
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From the Cloud Control console, right-click the target name, select Monitoring, and then All Metrics.
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From the All Metrics page, select the metric that you want to modify.
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Click Modify Thresholds.
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In the Modify Thresholds window, you can set values for settings such as:
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Warning Threshold
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Critical Threshold
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Occurrences Before Alert
Note:
You must have at least OPERATOR privilege on the target to make changes. Without OPERATOR privilege, the content of the Metric Threshold table is read-only.
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Click Save Thresholds to upload the new metric settings to the Management Repository.
Specifying Multiple Thresholds
The Specifying Multiple Thresholds functionality enables you to define various subsets of data that can have different thresholds. By specifying multiple thresholds, you can refine the data used to trigger alerts, which are one of the key benefits of using Enterprise Manager. The key in specifying multiple thresholds is to determine how the comparison relates to the metric threshold as a whole, and what benefit will be realized by defining a more stringent or lax threshold for that particular device, mount point, and so on.